The present invention relates to a thin film magnetic head and a method of manufacturing the thin film magnetic head.
An ordinary thin film magnetic head having a recording head section 10 and a reproducing head section 12 is shown in FIG. 6.
An insulating layer 14, which is made of, for example, alumina, is formed on a substrate 13, which is made of, for example, a ceramic. A lower shielding layer 15, which is made of, for example, FeNi, is formed on the insulating layer 14. An insulating layer 16, which is made of, for example, alumina, is formed on the lower shielding layer 15. An SAL (soft adjacent layer) 17, which is made of, for example, FeNi, is formed on the insulating layer 16. A spacer layer 18, which is made of, for example, tantalum, titanium, is formed on the SAL 17.
A pair of terminals 19 and 20 are formed on the spacer layer 18. An MR layer 21, which is made of FeNi, is formed on the spacer layer 18 and located between the terminals 19 and 20. An insulating layer 22, which is made of, for example, alumina, is formed on the terminals 19 and 20 and the MR layer 21. An upper shielding layer 23, which is made of, for example, FeNi, is formed on the insulating layer 22.
The insulating layer 14, the lower shielding layer 15, the insulating layer 16 the SAL 17, the spacer layer 18, the MR layer 21, the terminals 19 and 20, the insulating layer 22 and the upper shielding layer 23, etc. constitute the reproducing head section 12 for reproducing data.
An insulating layer 24, which is made of, foe example, alumina, is formed on the upper shielding layer 23. A coil 25 is formed in the insulating layer 24. An upper magnetic pole 26 is provided on the insulating layer 24. A protection layer 27, which is made of, for example, alumina, is formed on the upper magnetic pole 26. The upper shielding layer 23, the insulating layer 24, the coil 25, the upper magnetic pole 26 and the protection layer 27, etc. constitute the recording head section 10.
Note that, the upper shielding layer 23 also acts as a lower magnetic pole of the recording head section 10.
FIG. 7 shows a sectional view of the recording head section 10. The structure of the recording head section 10 will be explained with reference to FIG. 7.
The lower magnetic pole 23a, which is made of FeNi, is formed on the substrate 23 (the upper shielding layer 23) by plating. Thickness of the lower magnetic pole 23a is considerably thick, e.g., 6-7 xcexcm, so the lower magnetic pole 23a cannot be formed by spattering; therefore, it is made by electrolytic plating.
An insulating layer 28, which is made of, for example, alumina, is formed in a concave part 23b of the lower magnetic pole 23a and on the substrate 23 by spattering. The coil 25 is formed on the insulating layer 28 by plating.
The concave part 23b is filled with an insulating layer 29, which is made of resist and which covers over the coil 25.
A surface of the insulating layer 29 is flatly lapped until its level is made equal to that of the lower magnetic pole 23a. 
A high magnetic permeability layer 30, which is made of a high magnetic permeability material, e.g., CoFeNi, whose magnetic permeability is higher than that of the lower magnetic pole 23a, is formed on a surface of the lower magnetic pole 23a located on the write-end side, which faces the upper magnetic pole 26 with a gap layer 31. It is difficult to form the high magnetic permeability layer 30 by electrolytic plating; therefore, it is formed by spattering, and its thickness is about 0.5 xcexcm.
By forming the high magnetic permeability layer 30, a level difference is made between a surface of the high magnetic permeability layer 30 and a surface of the insulating layer 29.
The gap layer 31, which is made of, for example, SiO2, is formed on the surfaces of the high magnetic permeability layer 30 and the insulating layer 29.
Next, an insulating layer 32, which is made of resist, is formed on the gap layer 31, to correspond to the insulating layer 29 and a part of the high magnetic permeability layer 30 adjacent to the insulating layer 29.
By adjusting viscosity of the resist of the insulating layer 32, an apex part 33, whose thickness is made thinner toward the write-end (the left end in the drawing of FIG. 7), is formed in the insulating layer 32.
Next, the gap layer 31 and the insulating layer 32 are covered with resist so as to form a mask (not shown). Then, the upper magnetic pole 26 is formed by electrolytic plating. Further, the mask is removed, then the protection layer 27 is formed. By forming the protection layer 27, the thin film magnetic head is completed.
In the above described conventional thin film magnetic head, the high magnetic permeability layer 30 is formed in the vicinity of the gap layer 31 so as to improve recording ability, and the apex part 33 of the insulating layer 32 is located on the high magnetic permeability layer 30.
A distance xe2x80x9cGDxe2x80x9d between a front end of the apex part 33 and an end face of the gap layer 31 (or a disk-side face) is called a gap depth; and an inclination angle xe2x80x9cxcex8xe2x80x9d of the apex part 33 is called an apex angle.
The gap depth GD and the apex angle xcex8 highly influence characteristics of recording data.
If the gap distance GD is short, leakage a magnetic field is reduced and loss of a recording magnetic field, which is generated on the disk-side face side, is reduced, so that an over-write characteristic of the recording characteristics can be improved. However, if the gap depth GD is too short, e.g., 0.2 xcexcm or less, it is very difficult to correctly position a front end of the apex part 33, and the deviation of the front end badly influences the recording characteristics. The optimum gap depth GD is determined by considering the recording characteristics and manufacturing efficiency of the thin film magnetic head.
The apex angle xcex8 should be wide so as to reduce the leakage magnetic field between the lower magnetic pole 23 and the upper magnetic pole 26. However, if the apex angle xcex8 is too wide, it is difficult to form the upper magnetic pole 26. Therefore, the optimum apex angle xcex8 is determined by considering the recording characteristics and manufacturing efficiency of the thin film magnetic head as well as the gap depth GD.
Preferably, the gap depth GD and the apex angle xcex8 are independently controlled so as to make the recording characteristics optimum.
However, it is very difficult to independently control the gap depth GD and the apex angle xcex8 by adjusting the viscosity of the resist forming the insulating layer 32.
Namely, if the gap depth GD is changed, the apex angle xcex8 is simultaneously changed.
FIG. 8 is a graph showing a relationship between the gap depth GD and the apex angle xcex8. As clearly shown in FIG. 8, the apex angle xcex8 is made wider when the gap depth GD is reduced. The variation is influenced by sorts and viscosity of the resist.
As described above, it is very difficult to manufacture the thin film magnetic heads without limiting the variation of the gap depth GD and the apex angle xcex8, so that the variation of the recording characteristics of the thin film magnetic heads cannot be limited within a desired range.
An object of the present invention is to provide a thin film magnetic head having stable recording characteristics.
Another object of the present invention is to provide a method of manufacturing the thin film magnetic head, in which the gap depth GD and the apex angle xcex8 can be independently controlled.
To achieve the object, the present invention has following structures.
Namely, the thin film magnetic head of the present invention comprises: a lower magnetic pole; an upper magnetic pole; an insulating layer being formed between the lower magnetic pole and the upper magnetic pole, the insulating layer having a apex part which is formed in the vicinity of a write-end of the thin film magnetic head and whose thickness is made thinner toward the write-end; a coil being formed in the insulating layer; and a gap layer being formed between the write-end of the lower magnetic pole and the write-end of the upper magnetic pole which are faced each other, wherein the insulating layer includes a first insulating layer, a second insulating layer and a third insulating layer, the coil is provided in a concave part formed in the lower magnetic pole; the concave part is filled with the first insulating layer, which insulates the coil from the lower magnetic pole, a high magnetic permeability layer, whose magnetic permeability is higher than that of the lower magnetic pole, is formed on a surface of the lower magnetic pole which faces the upper magnetic pole at the write-end, the gap layer is formed on the high magnetic permeability layer, the second insulating layer is formed on the first insulating layer so as to make up a level difference between the high magnetic permeability layer and the first insulating layer, and the third insulating layer is formed on the second insulating layer and has the apex part.
In the thin film magnetic head, the third insulating layer may be a film of SiO2.
In the thin film magnetic head, the third insulating layer may be a film of Al2O3.
The method of the present invention is the method of manufacturing a thin film magnetic head, which comprises: a lower magnetic pole; an upper magnetic pole; an insulating layer being formed between the lower magnetic pole and the upper magnetic pole, the insulating layer having a apex part which is formed in the vicinity of a write-end of the thin film magnetic head and whose thickness is made thinner toward the write-end, the insulating layer including a first insulating layer, a second insulating layer, a third insulating layer and a fourth insulating layer; a coil being formed in the insulating layer; and a gap layer being formed between the write-end of the lower magnetic pole and the write-end of the upper magnetic pole which are faced each other, comprising the steps of: forming the lower magnetic pole, which has a concave part for accommodating the coil, in a substrate; forming the fourth insulating layer in the concave part; forming the coil on the fourth insulating layer; forming the first insulating layer which covers over the coil and fills the concave part; forming a high magnetic permeability layer, whose magnetic permeability is higher than that of the lower magnetic pole, on a surface of the lower magnetic part which faces the upper magnetic pole at the write-end; forming the gap layer on the high magnetic permeability layer; forming the second insulating layer on the first insulating layer so as to make up a level difference between the high magnetic permeability layer and the first insulating layer; forming the third insulating layer which covers the second insulating layer and which has the apex part; and forming an upper magnetic pole which covers over the gap layer and the third insulating layer.
In the method, the third insulating layer may be made of resist.
In the method, the third insulating layer may be a film of SiO2 or Al2O3 formed by spattering, and the apex part may be formed by ion milling.
In the thin film magnetic head of the present invention, the gap depth GD and the apex angle xcex8 can be fixed, so that stable recording characteristics can be gained.
In the method of the present invention, the gap depth GD and the apex angle xcex8 can be independently controlled during a process, so that they can be precisely formed.